[llvm] 66a163f - [DAG] GetDemandedBits - remove custom AND handling.

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2020-08-07T12:55:47+01:00
New Revision: 66a163f32817faa63e3717eb8ff1fe4188626c75

URL: https://github.com/llvm/llvm-project/commit/66a163f32817faa63e3717eb8ff1fe4188626c75
DIFF: https://github.com/llvm/llvm-project/commit/66a163f32817faa63e3717eb8ff1fe4188626c75.diff

LOG: [DAG] GetDemandedBits - remove custom AND handling.

As mentioned on D85463, we should be using SimplifyMultipleUseDemandedBits (which is the default fallback).

The minor regression in illegal-bitfield-loadstore.ll will be addressed properly by D77804.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    llvm/test/CodeGen/ARM/illegal-bitfield-loadstore.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e20e9055af94..04767a7ce37d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2248,18 +2248,6 @@ SDValue SelectionDAG::GetDemandedBits(SDValue V, const APInt &DemandedBits,
                        V.getOperand(1));
     }
     break;
-  case ISD::AND: {
-    // X & -1 -> X (ignoring bits which aren't demanded).
-    // Also handle the case where masked out bits in X are known to be zero.
-    if (ConstantSDNode *RHSC = isConstOrConstSplat(V.getOperand(1))) {
-      const APInt &AndVal = RHSC->getAPIntValue();
-      if (DemandedBits.isSubsetOf(AndVal) ||
-          DemandedBits.isSubsetOf(computeKnownBits(V.getOperand(0)).Zero |
-                                  AndVal))
-        return V.getOperand(0);
-    }
-    break;
-  }
   }
   return SDValue();
 }

diff  --git a/llvm/test/CodeGen/ARM/illegal-bitfield-loadstore.ll b/llvm/test/CodeGen/ARM/illegal-bitfield-loadstore.ll
index 93ba3fbc8530..2922e0ed5423 100644
--- a/llvm/test/CodeGen/ARM/illegal-bitfield-loadstore.ll
+++ b/llvm/test/CodeGen/ARM/illegal-bitfield-loadstore.ll
@@ -122,11 +122,12 @@ define void @i56_and_or(i56* %a) {
 ; BE-LABEL: i56_and_or:
 ; BE:       @ %bb.0:
 ; BE-NEXT:    mov r1, r0
+; BE-NEXT:    mov r2, #128
+; BE-NEXT:    ldrh r12, [r1, #4]!
+; BE-NEXT:    ldrb r3, [r1, #2]
+; BE-NEXT:    strb r2, [r1, #2]
+; BE-NEXT:    orr r2, r3, r12, lsl #8
 ; BE-NEXT:    ldr r12, [r0]
-; BE-NEXT:    ldrh r2, [r1, #4]!
-; BE-NEXT:    mov r3, #128
-; BE-NEXT:    strb r3, [r1, #2]
-; BE-NEXT:    lsl r2, r2, #8
 ; BE-NEXT:    orr r2, r2, r12, lsl #24
 ; BE-NEXT:    orr r2, r2, #384
 ; BE-NEXT:    lsr r3, r2, #8